Gastric Schwannoma: A Rare Case with Preoperative Diagnosis by EUS-FNB

Schwannomas are benign neurogenic tumors. Gastric schwannomas is the most common digestive tract. It account only for 0.2% of all gastric tumors and principally involve the submucosa and muscularis propria [1]. The preoperative differentiation between gastric schwannomas and gastrointestinal submucosal tumors Figure 1: EUS images (A, B) and pathologic findings (C-H) of EUS-FNB. The tissue was composed of broad bundles of elongated cells (C, H&E stain). In immunohistochemistry (D-H), the tumor strongly stains for S-100 (G) and moderately positive for SOX-10(H). Staining for CD-117(D), DOG-1(E) and smooth muscle desmin (F) are negative. (GISTs) can be difficult. None of the imaging studies have shown any distinct features unique to these neoplasms [2]. Final diagnosis of gastric schwannomas is made by surgical pathology. Both EUS-guided fine needle aspiration and EUS-guided biopsy (EUSFNB) can be used for tissue sampling. However only Endoscopic Ultrasound Guided Fine Needle Biopsy (EUS-FNB) allows core biopsy sufficient for histopathologic processing. With the advent of immunohistochemical staining techniques and ultrastructural evaluation, it is now possible to identify these neoplasms based on their distinct immunophenotypes [3].